1. Field of the Invention
The present invention relates to a lens holder apparatus used in a camera lens module, and more particularly to a camera lens module integrated to a lens holder capable of readjusting a focal length after combining respective lenses in the camera lens module.
2. Description of the Related Art
In general, an imaging device, such as a CCD (charge coupled device), is typically used for capturing an image in a video camera, an electronic steel camera, a PC camera terminal, PDA (Personal Digital Assistant) or the like. This is also referred to as “camera lens module.” In a conventional PDA for used in video communications, a photographing device containing the camera lens module is provided in a camera lens to enable a user to conduct video communications with others or photographs of a desired object. As such, the conventional PDA has been developed into a high performance, complex piece of machinery equipped with a camera, which can take a temporary image of the object and also store and transmit the image to another place. Such a camera lens module is configured so that an image of the object taken by the CCD through a lens and a diaphragm can be stored in a memory after the transformation into a digital signal using a signal transformer.
A CMOS image sensor is commonly used an image sensor. The CMOS image sensor is a device employing a switching system for sequentially detecting outputs using MOS transistors, which equals to the number of pixels. This type of CMOS technology adopts a control circuit and a signal processing circuit as peripheral circuits. The CMOS image sensor is significantly useful in a personal digital assistant (PDA), such as a mobile phone, since it is capable of operating with a minimum power consumption.
FIGS. 1 and 2 show a structure of a camera lens module 1 used in a conventional mobile phone. As shown the camera lens module 1 comprises an image sensor 3 provided on a printed circuit board 2 and a lens holder 4 fitted with an infrared filter 5 (IR filter) facing the image sensor 3. The lens holder 4 is formed at an upper portion of the lens holder 4 with a lens assembling portion 4a having a thread inside thereof, into which a lens barrel 8 sequentially combined with first and second lenses 6 and 7 is fastened. The lens barrel 8 is formed at the top thereof with a lens cap 9 for the purpose of protecting the lenses. A spacer for maintaining a gap between the lenses 6 and 7 is provided between the first and second lenses 6 and 7.
For an adjustment of focal lengths between the image sensor 3 and respective lenses 6 and 7, the lens barrel 8 is adapted to adjust the focal length by rotating to fasten the screw between an external thread 8a formed on the external surface of the lens barrel 8 and an internal thread 8b formed on the internal surface of the lens assembling portion 4a. Here, the lens barrel 8 is fixed in place by bonding with an epoxy resin. That is, when the focal lengths between the image sensor 3 and the lenses 6 and 7 are adjusted using the screw fastening of the lens barrel 8, the epoxy resin is used to bond the lens barrel.
In the conventional camera lens module of the above configuration, however, since the focal length is fixed in place using the epoxy resin after adjusting the focal length between the image sensor and the first and second lenses, it is impossible to readjust the focal length between the lenses and the sensor when the lens is incorrectly adjusted.